The long term objective of this proposal is to determine the components involved in the regulation of specific viral genes that participate in the process of oncogenic transformation by adenovirus 5. The regulation of the expression of the adenovirus region Elb genes will be examined in detail. Regulatory sequences which mediate the transcription of Elb DNA will be identified. The basic strategy is to analyze the effects of specific mutations in viral sequences on well defined Elb phenotypes. Viral sequences will be deleted in vitro and the regions containing deleted sequences will be replaced into viral DNA by recombination in vivo following transfection of permissive cells. The effects of specific deletions on ELB transcription will be assayed by DNA-RNA hybridization after infection with mutants under conditions where viral regulatory factors are deleted, or are provided only in trans. The source of trans-complementing viral genes will be another virus or a cell line that stably expresses the viral gene. The latter may be isolated by DNA-mediated gene transfer. Alternatively, the effects of sequence deletions on Elb transcription may be detected in vitro. Three specific questions will be addressed. First, whether a sequence can be identified that participates in positive transcriptional regulation by another viral gene (Specific Aim 1). Second, how the initiation of Elb transcription at two distinct sites is controlled (Specific Aim 2). Last, how a specific deletion mutant produces an elevated rate of Elb transcription (Specific Aim 3). These studies should reveal mechanisms of gene regulation that may operate not only in virus infected cells but also in the course of normal or abnormal cellular growth and development.